The use of gaskets for environmental sealing in aircraft, especially the outside of an aircraft, has some unique challenges. In its lifetime, an aircraft will undergo environmental extremes, pressures ranging from those typically found at sea level to the extremely air pressures found at 40,000-50,000 feet. Temperature ranges are also subject to extremes, as are humidity conditions and pressure differentials across a gasket.
Given such a radical and extreme environment, environmental seals, such as gaskets and gasket assemblies, especially those adapted for use on an aircraft exterior, must often have unique properties. Furthermore, the gaskets sometimes must be adapted to be conductive or nonconductive between the pieces that they join, depending upon their application. Furthermore, potential reactivity with the aircraft structures to which they engage is yet another consideration.